Why Are My Dog Or Cat’s ALT Blood Levels Abnormal

Alanine Aminotransferase ALT, previously called SGPT aka Glutamic Pyruvic Transaminase, GPT

Ron Hines DVM PhD

To see what normal blood and urine values are for your pet, go here

For an explanation of causes of most abnormal blood and urine tests go here

To see how tests are often grouped, go here

What To Do When My Dog Or Cat’s Liver Tests Are High?

The source of this enzyme are injured and leaking liver cells (hepatocytes). It is the frontline veterinary test for liver disease in dogs and cats.

Health Problems That Can Cause too Much ALT To Be Present In Your Dog Or Cat’s Blood:

Traditionally, veterinarians usually think of liver and bile duct disease.

But complex cholangiohepatitis, hepatic lipidosis and hyperthyroidism in cats, and pancreatitis, IBD and diabetes in both dogs and cats can also elevate ALT levels. In dogs, Cushing’s disease can be responsible. Exposure to toxins, certain medications and corticosteroid administration can also elevate your pet’s ALT level.

Heartworm disease or its treatment with Immiticide, hemolytic anemias, insufficient oxygen (hypoxia), metabolic disorders, over-exertion, severe body trauma and all the diseases that cause elevated AP can also elevate your pet’s ALT levels.

Mild increases in ALT can also occur in pregnancy and, as I mentioned before.  Hyperthyroidism can be responsible for moderately increased ALT levels in your cat. 

Significant gum/dental disease in your dog or cat can also moderately elevate its ALT levels . So can the NSAIDs given long term to dogs to treat arthritis (eg Rimadyl®, Deramaxx®, Previcox®,Metacam®, etc.). After the pet’s teeth are cleaned and antibiotics given; or the NSAID discontinued, It can take up to three weeks for ALT elevations due to either of those two causes to return to normal. (That article was sponsored by the testing laboratory, Idexx. So, naturally, it suggests a lot of testing.)

A hemolyzed blood samples – particularly if from a cat can give falsely-elevated ALT results.

On occasion, chronic hepatitis that can follow leptospirosis infection produces elevated liver function tests. (ref)

Health Problems That Can Cause Too Little ALT To Be Present:

I know of none. Have the test repeated at a National veterinary lab.

Complementary tests:

 fPL or cPL® for Pancreatitis, ultrasound examination, and all the complimentary tests suggested for elevated AP , often wise to repeated ALT test in 3 weeks and thereafter to monitor the situation. When liver cell damage is not continuing, ALT level should drop to one half in 1-3 days and be normal within 1-3 weeks.

Drugs associated elevated ALT are the ones that sometimes cause liver damage – the same ones that can raise AP levels. They include:
Corticosteroids, acetaminophen (Tylenol), Non-steroidals like Rimadyl and Metacam for arthritis, Griseofulvin for  ringworm infections, Halothane anesthetic, Ketoconazole anti-fungal medication, Mebendazole (Flagyl®) , anti-tumor medications, Methoyflurane anesthetic, Phenobarbital or primidone given for seizures, sulfonamide antibiotics and tetracycline.

It is not that unusual for a pet that appears healthy to occasionally have moderately higher than normal ALT, bilirubin or Alkaline Phosphatate levels with no apparent explanation. Physicians face the same problem as veterinarians when deciding what to do in those situations. (ref) I generally suggest that the test be repeated in 2-3 weeks to see if the results are still abnormal. Many times, they have improved. I am also more concerned when a number of liver-related tests are a bit high than when only one is. Of course, if your pet is feeling poorly, has lost weight or the result was quite high, waiting is not a good idea.


You are in the Vetspace animal health website